The aim of the proposed study is to determine factors related to relapse following treatment for heroin addiction, alcoholism, and cigarette smoking. Both the initial relapse episode and return to daily use will be studied. The primary variables to be studied are social support, coping skills, sex and situational characteristics. Subjects will be males and females, Blacks and Caucasians, between the age of 21 and 45. 1) The sample will consist of: 21-day outpatient heroin detoxification patients who are successfully completing treatment (n=90); 2) Cigarette smokers successfully completing a 21-day multimodality smoking treatment (n=90); and 3) Alcohol treatment patients successfully completing a 28-day inpatient treatment program (n=90). Within four days of treatment completion, subjects will be given an intake assessment battery which includes demographic items, measures to assess commitment to abstinence, social functioning, coping skills, social support, withdrawal symptoms, stress, and drug use. Subjects will be followed weekly for twelve weeks following treatment, and assessed weekly on drug use, withdrawal symptoms, and stress. If relapse occurs, a relapse episode questionnaire will be given. Self-report of drug use will be validated by urine assays.